Leather-stretching device.



No. 680,840. 7 Patented Aug. 20, IQUI.

J. CALDWELL.

LEATHER STRETCHING DEVICE.

(Application filed Dec. 22, 1900. (No Model.) 7 2 Sheets-$heet 2,

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titre Ans AlENT FFICE.

JOHN CALDWELL, OF MINNEAPOLIS, MINNESOTA, ASSIGNOR TO THE W. S. NOTT COMPANY, OF SAME PLACE.

LEATHER STR ETCHINIG DEVlCE.

SPECIFICATION forming part Of Letters Patent N0. 680,840, dated August 20, 1901. Application filed December 22, 1900. Serial No. 40,714. (No model.)

To aZZ whom, it may concern:

Be it known that I,JOHN CALDWELL, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented certain new and useful Improvements in Leather Stretching Devices, of which the following is a specification.

My invention relates to leather-stretching machines used in the preparation of leather for the manufacture of belting, which machines employ a detachable frame having heads that support the leather by means of a series of independent holders adapted to engage marginal portions of the leather and to be adjustably connected to the heads.

The object of the invention is to provide independent holders arranged to be adjusted in paths parallel with each other and with the direction of the tension of the machine and adapted to engage short marginal sections of the leather at right angles to the axis of its body and to be successively coupled to the head at proper times duringthe operation of the machine for the purpose of stretching difierent longitudinal sections of the body of leather to an unequal extent, so that each portion may be subjected to the degree of tension relative to other portions that is deemed necessary to properly prepare the body as a whole for the use to which it is to be put.

In the preparation of a hide for belting the shoulder portion is cut off on a straight line, the belly portion as far up as the flank is also removed,and the remainder is then out lengthwise into three pieces, a center (of about eighteen inches width) and two sides, or it is split down the middle into two parts, commonly called backs, and these divisions are afterward soaked in water, partly dried, and greased. This process causes the side portions, which are comparatively soft and spongy, to contract relatively more than the portions nearer the middle of the hide, which are firmer and less porous, and the effect upon the backs is to cause their inner edges to bow outward and the outer edges to bow inward, and the effect upon the centers is to cause their middle portions to buckle. When in this condition, different parts of the leather are capable of being stretched to a varying extent without detriment to their fiber or strength-that is, while the softer portions may be stretched from about five to seven inches the harder portions, especially alone the backbone,cannot be stretched more than about four inches Without injury. It is therefore impossible to properly stretch all portions of a center or back or side of leather by means of clamps or other holders that extend entirely across its ends and engage and hold all portions of the margins at all times during the operation of the machine, for all portions are thus subjected to the same degree and duration of tension; but by means of my improved devices the portions requiring different degrees of stretching may be successively subjected to tension at the will of the operator so that as a result all portions of the center or back or side of leather are stretched to the extent desired, the bowed edges made almost if not quite straight, and a considerable saving of leather at both edges, as well as at the irregular end effected. Such improvements are illustrated in the accompanying drawings, in which Figure 1 is a plan view of parts of a stretcher frame and head provided with my improvements. Fig. 2 is a longitudinal section of the same on the line w w of Fig. 1. Fig. 3 shows a variation of the means for engaging the leather. Fig. 4 is a sectional View of the same on the line was of Fig. 3. Fig. 5 is a plan view showing a strip of leather and several of the holders in use in connection with the stationary stretcher-head, andFig. 6 is also a plan View showing a full set of the holders in use on the movable head for stretching a back of leather. 7

In the drawings, 1 designates the side rails of an ordinary stretcher-frame, 2 the stationary head, that is attached to the sides, and 3 the movable head, which is arranged to slide and be guided lengthwise of. the frame, the two heads furnishing the means for supporting and stretching the leather. This stretcherframe is intended to be placed temporarily on a table or other support adjacent to the power mechanism of a stretching-machine, so that power can be applied to the slidable head and the frame and leather removed from the ma chine when desired.

The head (2 or 3) which is to be used for holding a straight end of leather may be pro.- vided with a transverse row of permanent tines 4:, a clamp, or any other suitable means (including the devices of my present improve-, ment) for engaging and holding such end of leather. The head for holding the irregular end of the leather is provided with a plate 5 on its upper surface, having a suitable number of slots 6 or other suitable guideways extending parallel with the frame sides 1 for guiding,the movements of the leather-holders. The latter are carried on plates, bases, or bodies '7, which seat loosely on the headplate 5 and have downward lugs 8 or other means for guiding them in their movements by engagement in the slots 6 or guideways to prevent lateral or turning movements.

The means for engaging the leather may.

comprise devices in the nature of clamps or grippers supported on the bases 7.

ward through slots in the upper jaws, or, as illustrated in Figs. 3 to 6, the bases 7 may be provided with one or more rows of tines 15, adapted to be forced through the leather and hold it, or any other devices adapted to engage and hold a margin of the leather may be provided on the bases 7, for-the specific means for engaging the leather is not material to the present invention.

For the purpose of enabling the holderbases to be locked at the timesand places desired-the plate 5 is provided with racks 16 or serrations, corrugations, or equivalent means adjacent to the slots 6, and in each slot is a bolt 17 or other-device carryinga plate 18 or other device that is provided with dogs or serrations adapted to interlock with or engage the'racks 16 at the sides of the slots, and the bolt'ha's an angular portion 19 to prevent it from rotation in the slot and'a threaded upper'portion to receive a nut 20. The upper portion of the bolt being'passed through an opening in the holder-plate 7, the nut may be turned on the bolt to lift it and raise the locking-head 18 to engagement with the rack, and thus clamp the holder in place. The racks might be provided on the upper surface instead of the lower surface of the plate 5 and different means might be employed for engaging them without changing the mode of operation of the improvements.

The manner of putting the devices to practical use for stretching a piece of leather that hasan uneven end or'which requires more stretching in some parts than others is illustrated in Figs. 5 and 6. In these figures the direction of the tension upon the leather is indicated by the arrows .2. In Fig. 5 thestationary head is shown, and the holders (indi- In Figs. l and 2 such devices are shown to consist of vertically-movable upper jaws 9, hinged to v the bases by pintles 10,passing throughstand' ardsll on the bases and ears 12 on the jaws; 9. The jaws may be operated to grip the leather by means of nuts 13 on threadedstuds 14, that are fast to the bases and extend up-.

cated for convenience by the letters a b 0 cl, 85c.) serve merely to hold the leather, while in Fig. 6 the holders are shown as connected to the movable head, and hence serve to pull the leather. For the purpose of more clearly illustrating the mode of operation and the effect upon the leather the holders are shown merely in outline, and the relative extent of their movements, as well as their effect in stretching and straightening the leather, are exaggerated. In Fig. 5 the piece of leather L selected for illustration is one in which the shorter side is the softer and requires most stretching. The holder at, engaging the shorter side, is therefore first secured to the plate 5 by turning its locking-nut 20. The locking position of the nuts is indicated in Figs. 5 and 6, showing their wings 21 at right angles to the slots and the unlocked position by showing their wings parallel with the slots. Power is then applied to the other head and the leather is stretched until its free end portion is moved from the position indicated by the full line m to that indicated by the first dotted line n. The holder Z) is then locked, and the leather, being then held by the holders a and b, is-stretched until its free end portion is brought to the position indicated by the second dotted line 0, when the holders 0 and d are locked and the stretching is continued as long as deemed desirable. In Fig. 6 the body of leather L is assumed to be a back with its edges bowed, its shorter margin soft and spongy, its lower margin hard and firm, and the intermediate portions varying in fiber between the extremes of the margins. Here the holders a b c are shown to be locked for the initial work, and when the end of the leather has beenpulled by them to the position indicated by the first dotted line nthe holder (1 may be locked, when the margin has reached the line 0 the holders 6 andf may be locked, and, lastly, when the line 19 is reached the remaining holders gand h maybe put to work, and the entire set may then be used to subject the leather as-a whole to the additional tension. The operation not only lengthens the leather, but eliminates or reduces whatever lateral bow it may have had, its progressive movement laterally toward straight lines being indicated by the full lines 1- and the broken lines 5,25, u, and o.

It is preferable to have all of the series of holders secured to the leather beforepower is applied, so that the operator can quickly put them to work by merely turning their locking-nuts, and in this way he can successively operate or disconnect such of the holdders as in his judgment will produce the'best results. It isto be understood that it is necessarily left with the operator to judge of the proper extent of stretching to be done by the working holders before the next in the series are put to Work.

The features of invention set forth and not claimed herein relative to the means for engaging marginal portions of the leather and the means for adjusting, guiding, and independently securing the holders to the head are reserved to be claimed in my pending applications, Serial No. 738,820, filed December 1, 1899; Serial No. 1,424, filed January 15, 1900; Serial No. 39,844, filed December 14, 1900, and Serial No. 40,239, filed December 18,1900, and the method or process of stretching leather for belting herein suggested is reserved to be claimed in my pending application, Serial No. 51,296, filed March 15, 1901.

Having described my invention What I claim is- 1. The combination with a stretcher-head having guide-slots extending longitudinally of the stretcher-frame, of a series of independently-slidable leather-holders thereon guided by said slots, and a series of locking devices carried by the holders and adapted to lock them to the head, substantially as set forth.

2. The combination with a stretcher-head having slots extending longitudinally of the stretcher-frame and serrations or like irregularities of surface, of a series of independently-slidable leather-holders thereon guided by said slots, and a series of locking devices carried by the holders and adapted to engage such serrations and look the holders to the head, substantially as set forth.

8. The combination with the head of a stretcher-frame provided with guide-slots extending parallel With the frame sides and serrations or like irregularities of surface, of a series of leather-holders thereon independently slidable in said slots but having no lateral movement, and means for separately locking such holders to the head, substantially as set forth.

4. In a stretching-machine, the combination witha stretcher-head having guide-slots extending parallel With the direct-ion of tension of the machine, of a series of independent leather-holders slidable along and guided by said slots, and locking devices carried by the holders for independently and successively locking them on the head, substantially as set forth.

5. In aleather-stretchin g machine,the.combination with a stretcher-head provided with a series of parallel guide-slots extending in the direction of movement of the stretching mechanism, a corresponding series of mov= able independent holders arranged to engage an end of a body of leather at right angles to its axis and provided with means for connectin g them independently in said. guide slots to control the direction of their move ments, and means for locking selected holders of the series in succession to the head, substantially as set forth.

6. In a leather-stretching machine,the combination with a stretcher-head, of a series of independent holders supported thereon in en= gagement with the end of a piece of leather and arranged to be moved independently of said head by the leather in the direction it is moved by the stretching mechanism, guides on said head for controlling such movements of the holders, and means for lockin g selected holders of the series to the fixed head and unlocking them at will,substantially as set forth.

In testimony whereof I have hereunto set my hand this 10th day of December, 1900.

JOHN CALDWELL.

In presence of- P. H. GUNOKEL, A. L. WHELAN. 

